Reduced levels of Cacna1c attenuate mesolimbic dopamine system function

Area of Science:

• Neuroscience
• Genetics
• Pharmacology

Background:

• Genetic variations in CACNA1C, encoding the L-type calcium channel (LTCC) Ca_v 1.2, are linked to psychiatric disorders like bipolar disorder, depression, and schizophrenia.
• The mesolimbic-dopamine (ML-DA) system is implicated in these disorders, with LTCCs playing a role in dopamine neurotransmission between the ventral tegmental area (VTA) and nucleus accumbens (NAc).

Purpose of the Study:

• To investigate how CACNA1C gene variations affect dopamine-mediated behaviors and the ML-DA system.
• To determine the specific role of Cacna1c in the VTA and NAc in responses to psychomotor stimulants.

Main Methods:

• Utilized constitutive and conditional knockout mice lacking Cacna1c.
• Administered the LTCC antagonist nimodipine and DAT antagonist GBR12909.
• Measured dopamine release and reuptake in the NAc using fast-scan cyclic voltammetry.
• Assessed behavioral responses, including hyperlocomotion and locomotor sensitization.

Main Results:

• Cacna1c haploinsufficiency altered dopamine transporter (DAT) sensitivity in dopamine release.
• Mice with constitutive Cacna1c haploinsufficiency showed reduced hyperlocomotion and attenuated locomotor sensitization to DAT stimulants.
• Selective reduction of Cacna1c in the VTA, but not NAc, impaired behavioral sensitization to GBR12909.
• Nimodipine administration attenuated GBR12909-induced sensitization.

Conclusions:

• Cacna1c is critical for normal behavioral responses to dopamine stimulants.
• Cacna1c activity within the VTA is essential for the development of behavioral sensitization.
• These findings suggest Cacna1c influences presynaptic ML-DA system function, potentially modifying psychiatric disorder risk.